MANILA, Nov 17 (Reuters) - U.S. corn futures traded near one-year lows on Friday and were set to post their biggest weekly fall in a month after U.S. export sales came in below market expectations and forecasts pointed to plentiful supply.

Wheat edged higher, but was also on track for its deepest weekly drop in a month, as were soybeans.

The most-traded corn contract for December delivery on the Chicago Board of Trade was up 0.2 percent at $3.37-1/4 a bushel by 0616 GMT.

That’s just slightly above Thursday’s trough of $3.36-1/4, lowest since Nov. 15 last year. For the week, corn has lost 1.8 percent so far.

Net U.S. old-crop corn export sales last week fell to 949,500 tonnes, below market expectations for at least 1.2 million tonnes, data from the U.S. Department of Agriculture showed on Thursday.

Analytics firm Informa Economics at the same time raised its forecast of U.S. 2018 corn plantings to 91.415 million acres, from 90.460 million acres previously.

While corn plantings elsewhere, particularly in Brazil, will fall year-on-year, “crops are otherwise seeing limited disruption so far, prompting speculative positions to again approach multi-year lows,” according to BMI Research, a unit of Fitch Group.

CBOT soybeans were up 0.3 percent at $9.75 a bushel, but have shed 1.3 percent so far this week. Wheat gained 0.7 percent to $4.24-1/4 a bushel, but was down 1.7 percent on week.

U.S. net old-crop soybean sales of 1.1 million tonnes last week were at the low end of a range of trade estimates, the USDA data showed. U.S. wheat sales of 489,300 tonnes were down 37 percent from the previous week.

Chicago wheat prices remain near recent lows and “the market has perhaps found a modicum of stability here,” said Tobin Gorey, analyst at Commonwealth Bank of Australia.

“While (European Union) prices are stable, and so is the greenback, the Chicago market now probably has little impetus to move unless U.S. exports slow materially,” Gorey said in a note. (Reporting by Manolo Serapio Jr.; Editing by Tom Hogue and Biju Dwarakanath)